CN110045187A - Gird-connected inverter electric network impedance discrimination method based on high frequency electrocardiography - Google Patents
Gird-connected inverter electric network impedance discrimination method based on high frequency electrocardiography Download PDFInfo
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Abstract
The invention proposes a kind of gird-connected inverter electric network impedance discrimination method based on high frequency electrocardiography, first, the voltage and bridge arm side electric current for being measured gird-connected inverter respectively using voltage sensor and current sensor are carried out transformation to voltage and bridge arm side electric current by pi controller and obtain modulated voltage signal；Then, three-phase high-frequency voltage signal is injected in modulated voltage signal to the voltage for updating gird-connected inverter, and the grid side electric current of gird-connected inverter is measured using current sensor, then updated voltage and grid side electric current are substituted into voltage subtraction module and current draw module respectively；Finally, the high-frequency voltage signal and high-frequency current signal of the power grid of gird-connected inverter are extracted using improved complex filter, thus the impedance value of Real-time solution power grid.The present invention is superimposed three-phase high-frequency voltage signal directly on modulated voltage signal, it is ensured that high-frequency signal is efficiently injected into, and can be improved the signal-to-noise ratio of power grid, and then improve electric network impedance identification precision.
Description
Technical field
The present invention relates to power electronics fields, particularly relate to a kind of gird-connected inverter electricity based on high frequency electrocardiography
Net impedance discrimination method.
Background technique
In recent years, with the rapid expansion of new-energy grid-connected inverter installation scale, power grid more and more shows " weak
The characteristic of power grid ", impedance is also increasing, and produces tremendous influence to the stable operation of gird-connected inverter.In order to mention
The operation stability of gird-connected inverter under high weak grid, it is necessary to real-time identification be carried out to electric network impedance, and according to electric network impedance value
The operational mode of adjustment gird-connected inverter in real time.Common electric network impedance discrimination method mainly includes passive means and active method two
Class.Passive means calculate electric network impedance by the intrinsic voltage and current harmonic wave of detection power grid, and this method will not increase to power grid
Add harmonic disturbance, but since noise is relatively low, causes the impedance identification precision of passive means lower.Active method passes through into power grid
The voltage harmonic of injection properties frequency, and the harmonic current of power grid is extracted, to realize that electric network impedance recognizes, active method passes through note
Entering high-frequency signal can be improved signal-to-noise ratio, to improve electric network impedance identification precision, therefore its application is wider.
There are many electric network impedance discrimination method application patents at present, such as application No. is 201710113861.4,
The verification method and experimental provision of entitled electric network impedance identification propose a kind of electric network impedance discrimination method and experiment dress
It sets, this method keeps gird-connected inverter defeated by injecting high-frequency current signal into current reference value, and by closed-loop current control
It include out injected high-frequency signal in electric current and voltage；Although electric network impedance identification may be implemented in this method, but due to electric current
Ring pi controller can only realize DAZ gene to direct current signal, and cannot achieve and realize to the high-frequency signal injected
DAZ gene causes the high-frequency signal effect being actually implanted into poor.Such as application No. is 201710361584.9, denomination of invention
For a kind of electric network impedance on-line identification method and device based on PRBS disturbance injection, propose a kind of based on PRBS disturbance injection
Electric network impedance on-line identification method and device and document [based on more under Yang Ying, Zhang Xing, Li Ming is uneven and harmonic
Electric network impedance detection method [J] power supply journal of module complex filter, 2018,16 (2): 69-75.] propose a kind of consideration
The electric network impedance discrimination method of unbalanced power supply harmony wave action, these methods are required to the overlapped high-frequency disturbance letter in electric current
Number, it is therefore desirable to rationally design electric current loop pi controller, be likely to guarantee gird-connected inverter reality output electric current and
Contain corresponding high-frequency signal in voltage signal.
Application No. is 201820339286.X, utility model is entitled based on the identification circuit recognized in line impedence, proposes
A kind of impedance identification circuit and method, this method sample injection letter by the Injection Current pulse signal into current-order
Network voltage and current signal after number obtain electric network impedance by analytical calculation, and that there are calculation amounts is larger for this method, it is multiple to realize
The problems such as miscellaneous.
Summary of the invention
Effective high-frequency signal cannot be injected for existing electric network impedance discrimination method and is not accounted for voltage and electricity
Direct current biasing is introduced in stream sampling channel, so that the technical problem that the identification precision of electric network impedance is lower, the invention proposes one
Gird-connected inverter electric network impedance discrimination method of the kind based on high frequency electrocardiography, firstly, being injected in three-phase modulations voltage signal
Three-phase high-frequency voltage signal can realize high-frequency signal without changing the original pi controller parameter of electric current loop
Injection.Secondly, increasing a high-pass filter on the basis of complex filter carries out high-frequency voltage signal and high-frequency current
Signal extraction can eliminate the influence that the direct current biasing introduced in voltage and current sample channel recognizes impedance, thus into one
Step improves electric network impedance identification precision.
The technical scheme of the present invention is realized as follows:
A kind of gird-connected inverter electric network impedance discrimination method based on high frequency electrocardiography, its step are as follows:
S1, it is sampled to obtain the line voltage u of gird-connected inverter using power grid of the voltage sensor to gird-connected invertergab
With line voltage ugbc, the phase voltage u of three phase network is calculatedga, phase voltage ugbWith phase voltage ugc, and by phase voltage uga, mutually electricity
Press ugbWith phase voltage ugcIt transforms in the static DQ coordinate system of two-phase, obtains voltage ugDWith voltage ugQ, and by voltage ugDAnd voltage
ugQPhaselocked loop is substituted into obtain the synchronization angular frequency of power grid0And angle, θ0；
S2, sampling acquisition three-phase current i is carried out using bridge arm side electric current of the current sensor to gird-connected invertera, three-phase
Electric current ibWith three-phase current ic, and by three-phase current ia, three-phase current ibWith three-phase current icTransform to the static DQ coordinate system of two-phase
In, obtaining two current components is respectively electric current iDWith electric current iQ, recycle angle, θ0By electric current iDWith electric current iQIt is mapped to synchronization
Obtaining two current components on rotation dq coordinate system is respectively electric current idWith electric current iq；
S3, setting electric current reference value are electric current idrefWith electric current iqref, by electric current idref, electric current iqrefIt is obtained with step S2
Electric current id, electric current iqThe modulated voltage signal u in synchronous rotary dq coordinate system is obtained by pi controllerdrefAnd tune
Voltage signal u processedqref, then by modulated voltage signal udrefWith modulated voltage signal uqrefIt transforms in the static DQ coordinate system of two-phase
Obtain modulated voltage signal uDrefWith modulated voltage signal uQref；
S4, the modulated voltage signal u for obtaining step S3DrefWith modulated voltage signal uQrefTransform to three phase static abc seat
In mark system, obtaining three modulated voltage signals is respectively modulated voltage signal uaref, modulated voltage signal ubrefBelieve with modulation voltage
Number ucref, then by high-frequency signal uah, high-frequency signal ubhWith high-frequency signal uchIt is injected separately into modulated voltage signal uaref, modulation voltage
Signal ubrefWith modulated voltage signal ucrefObtaining three-phase modulations voltage signal is respectively modulated voltage signal uahref, modulation voltage
Signal ubhrefWith modulated voltage signal uchref；
S5, the modulated voltage signal u for obtaining step S4ahref, modulated voltage signal ubhrefWith modulated voltage signal uchref
It is input to PWM modulation unit, exports 6 road pwm signals, and be input to pwm signal by the control system in gird-connected inverter
In gird-connected inverter, the voltage u in step S1 is updatedgDWith voltage ugQ；
S6, the voltage u for obtaining step S5gDWith voltage ugQU is substituted into respectivelyDhExtraction module and uQhExtraction module, using changing
Into complex filter respectively to uDhExtraction module and uQhExtraction module extracts operation, obtains high-frequency voltage signal uDhWith
High-frequency voltage signal uQh；
S7, it is sampled to obtain three-phase current i using electric current of the current sensor to gird-connected inverter grid sidega, three-phase
Electric current igbWith three-phase current igc, and by three-phase current iga, three-phase current igbWith three-phase current igcThe static DQ of two-phase is transformed to sit
In mark system, obtaining two current components is respectively electric current igDWith electric current igQ；
S8, the electric current i for obtaining step S7gDWith electric current igQI is substituted into respectivelyDhExtraction module and iQhExtraction module, by changing
Into complex filter respectively to iDhExtraction module and iQhExtraction module extracts operation, obtains high-frequency current signal iDhWith
High-frequency current signal iQh；
S9, the high-frequency voltage signal u obtained according to step S6Dh, high-frequency voltage signal uQhThe high-frequency electrical obtained with step S8
Flow signal iDh, high-frequency current signal iQhCalculate the resistance value of the power grid of gird-connected inverterAnd inductance valueAnd then obtain power grid
Impedance value.
Preferably, the voltage u in the step S1gDWith voltage ugQAre as follows:
Wherein,Then utilize voltage ugDAnd electricity
Press ugQThe angle, θ of power grid is calculated0Are as follows:The synchronization angular frequency of power grid0Are as follows:
Preferably, the electric current i in the step S2dWith electric current iqAre as follows:
Wherein,
Preferably, the modulated voltage signal u in the step S3DrefWith modulated voltage signal uQrefAre as follows:
Wherein,k1For proportional integration tune
Save the proportionality coefficient of device, k2For the integral coefficient of proportional and integral controller, s is Laplace operator.
Preferably, the modulated voltage signal u in the step S4ahref, modulated voltage signal ubhrefAnd modulated voltage signal
uchrefIt is respectively as follows:
Wherein,
UhAmplitude for the high-frequency signal injected, t represent the time.
Preferably, the high-frequency voltage signal u in the step S6DhWith high-frequency voltage signal uQhExtracting method are as follows:
S61, the voltage u obtained using step S5gDWith voltage ugQCalculate separately error voltage signal ugDerr1With error electricity
Press signal ugQerr1:Wherein, ugDAnd ugQVoltage respectively on the static DQ coordinate system of two-phase, uDh
And uQhIt is high-frequency voltage signal to be extracted,WithIt is network voltage positive-sequence component；
S62, high-pass filter is utilizedThe error voltage signal u that step S61 is obtainedgDerr1And error voltage signal
ugQerr1It is filtered, obtains error voltage signal ugDerrWith error voltage signal ugQerr:
S63, the error voltage signal u obtained according to step S62gDerrWith error voltage signal ugQerrCalculate high frequency voltage
Signal uDh, high-frequency voltage signal uQh, network voltage positive-sequence componentNetwork voltage positive-sequence component
Wherein, ωhc,uFor high-frequency voltage signal uDhExtraction unit and high-frequency voltage signal uQhThe cutoff frequency of extraction unit,
ωc,uFor network voltage positive sequence voltageExtraction unit and network voltage positive sequence voltageThe cutoff frequency of extraction unit, ω0For
The synchronization angular frequency of power grid,θ0For the angle of power grid,J represents imaginary number；
S64, the high-frequency voltage signal u for obtaining step S63Dh, high-frequency voltage signal uQh, network voltage positive-sequence component
With network voltage positive-sequence componentIt substitutes into step S61, updates error voltage signal ugDerr1With error voltage signal ugQerr1；
S65, step S61 to step S64 is repeated, out of service when reaching the command signal of setting, output mentions
High-frequency voltage signal u after takingDhWith high-frequency voltage signal uQh。
Preferably, the electric current i in the step S7gDWith electric current igQAre as follows:
Preferably, the high-frequency current signal i in the step S8DhWith high-frequency current signal iQhExtracting method are as follows:
S81, the electric current i obtained using step S7gDWith electric current igQCalculate separately error current signal igDerr1With error electricity
Flow signal igQerr1:Wherein, igDAnd igQElectric current respectively under the static DQ coordinate system of two-phase, iDhWith
iQhIt is high-frequency current signal to be extracted,WithIt is power network current positive-sequence component；
S82, the error current signal i that step S81 is obtained using high-pass filtergDerr1With error current signal igQerr1
It is filtered, obtains error current signal igDerrWith error current signal igQerr:
S83, the error current signal i obtained according to step S82gDerrWith error current signal igQerrCalculate high-frequency current
Signal iDh, high-frequency current signal iQh, power network current positive-sequence componentPower network current positive-sequence component
Wherein, ωhc,iFor high-frequency current signal iDhWith high-frequency current signal iQhThe cutoff frequency of extraction unit, and ωhc,i
=ωhc,u, ωc,iFor power network current positive-sequence componentWith power network current positive-sequence componentThe cutoff frequency of extraction unit, ωc,i=
ωc,u；
S84, the high-frequency current signal i for obtaining step S83Dh, high-frequency current signal iQh, power network current positive-sequence component
With power network current positive-sequence componentIt substitutes into step S81 and updates error current signal igDerr1With error current signal igQerr1；
S85, step S81 to step S84 is repeated, out of service when reaching the command signal of setting, output mentions
High-frequency current signal i after takingDhWith high-frequency current signal iQh。
Preferably, the resistance value of the power gridAnd inductance valueAre as follows:
It is that the technical program can generate the utility model has the advantages that compared with the conventional method, the present invention does not select on current-order
Overlapped high-frequency signal, but three-phase high-frequency voltage signal is superimposed directly on modulated voltage signal, it is ensured that high-frequency signal has
Effect injection, and do not need to remodify modulation electric current loop pi controller, and the present invention is on the basis of complex filter
On increase high-pass filter, the direct current biasing introduced in the sampling channel of voltage and the sampling channel of electric current can be eliminated, mentioned
High electric network impedance identification precision.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this
Some embodiments of invention for those of ordinary skill in the art without creative efforts, can be with
It obtains other drawings based on these drawings.
Fig. 1 is that electric network impedance of the invention recognizes module overall structure diagram.
Fig. 2 is the high frequency voltage u in Fig. 1DhExtraction module structural schematic diagram.
Fig. 3 is the high frequency voltage u in Fig. 1QhExtraction module structural schematic diagram.
Fig. 4 is the high-frequency current i in Fig. 1DhExtraction module structural schematic diagram.
Fig. 5 is the high-frequency current i in Fig. 1QhExtraction module structural schematic diagram.
Fig. 6 is overall structure diagram of the invention.
Fig. 7 is the document [power grid based on multimode complex filter under Yang Ying, Zhang Xing, Li Ming is uneven and harmonic
Impedance detection method [J] power supply journal, 2018,16 (2): 69-75.] impedance identification and simulation result figure.
Fig. 8 is the local result figure of region A in Fig. 7.
Fig. 9 is impedance identification and simulation result figure of the invention.
Figure 10 is the local result figure of region B in Fig. 9.
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation description, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on
Embodiment in the present invention, those of ordinary skill in the art are obtained every other under that premise of not paying creative labor
Embodiment shall fall within the protection scope of the present invention.
As shown in figures 1 to 6, the invention proposes a kind of, and the gird-connected inverter electric network impedance based on high frequency electrocardiography is distinguished
Knowledge method passes through firstly, obtaining the voltage of gird-connected inverter and the electric current of bridge arm side using voltage sensor and current sensor
Proportional integrator carries out transformation to the electric current of voltage and bridge arm side and obtains modulated voltage signal；Then, three-phase high frequency voltage is believed
Number injection modulated voltage signal in update gird-connected inverter voltage, and using current sensor obtain gird-connected inverter power grid
The electric current of side, then updated voltage and the electric current of grid side are substituted into voltage subtraction module and current draw module respectively；Most
Afterwards, the high-frequency voltage signal and high-frequency current signal of the power grid of gird-connected inverter are extracted using improved complex filter, thus
The impedance value of Real-time solution power grid, the specific steps are as follows:
S1, it is sampled to obtain the line voltage u of gird-connected inverter using power grid of the voltage sensor to gird-connected invertergab
With line voltage ugbc, and by formula (1) to line voltage ugabWith line voltage ugbcCarry out the phase voltage that three phase network is calculated
uga, phase voltage ugbWith phase voltage ugc:
Further according to formula (2) by phase voltage uga, phase voltage ugbWith phase voltage ugcIt transforms in the static DQ coordinate system of two-phase,
Obtain voltage ugDWith voltage ugQ:
Then by voltage ugDWith voltage ugQPhaselocked loop is substituted into obtain the synchronization angular frequency of power grid0And angle, θ0,
S2, sampling acquisition three-phase current i is carried out using bridge arm side electric current of the current sensor to gird-connected invertera, three-phase
Electric current ibWith three-phase current ic, and according to formula (3) by three-phase current ia, three-phase current ibWith three-phase current icIt is quiet to transform to two-phase
Only in DQ coordinate system, obtaining two current components is respectively electric current iDWith electric current iQ:
Further according to formula (4) by electric current iDWith electric current iQIt is mapped on synchronous rotary dq coordinate system and obtains two current components
Respectively electric current idWith electric current iq:
Wherein, θ0For the angle of power grid.
S3, setting electric current reference value are electric current idrefWith electric current iqref, according to formula (5) by electric current idref, electric current iqrefWith
Electric current i in step S2d, electric current iqThe modulated voltage signal in synchronous rotary dq coordinate system is obtained by pi controller
udrefWith modulated voltage signal uqref:
Further according to formula (6) by modulated voltage signal udrefWith modulated voltage signal uqrefTransform to the static DQ coordinate of two-phase
In system, obtaining two modulated voltage signals is respectively modulated voltage signal uDrefWith modulated voltage signal uQref:
Wherein, k1For the proportionality coefficient of proportional and integral controller, k2For the integral coefficient of proportional and integral controller, s is that drawing is general
Laplacian operater.
S4, the modulated voltage signal u for being obtained step S3 according to formula (7)DrefWith modulated voltage signal uQrefTransform to three
In mutually static abc coordinate system, obtaining three modulated voltage signals is respectively modulated voltage signal uaref, modulated voltage signal ubref
With modulated voltage signal ucrefIt is respectively as follows:
Further according to formula (8) by high-frequency signal uah, high-frequency signal ubhWith high-frequency signal uchInject modulated voltage signal
uaref, modulated voltage signal ubrefWith modulated voltage signal ucrefObtaining three-phase modulations voltage signal is respectively modulated voltage signal
uahref, modulated voltage signal ubhrefWith modulated voltage signal uchref:
Wherein,
UhAmplitude for the high-frequency signal injected, t represent the time.
S5, the modulated voltage signal u for obtaining step S4ahref, modulated voltage signal ubhrefWith modulated voltage signal uchref
It is input to PWM modulation unit, exports 6 road pwm signals, and be input to pwm signal by the control system in gird-connected inverter
In gird-connected inverter, the voltage u in step S1 is updatedgDWith voltage ugQ。
S6, as shown in Figures 2 and 3, the voltage u that step S5 is obtainedgDWith voltage ugQU is substituted into respectivelyDhExtraction module and uQh
Extraction module, using improved complex filter respectively to uDhExtraction module and uQhExtraction module extracts operation, obtains high
Frequency voltage signal uDhWith high-frequency voltage signal uQh, the specific steps of which are as follows:
S61, the voltage u obtained using step S5gDWith voltage ugQCalculate separately error voltage signal ugDerr1With error electricity
Press signal ugQerr1:
Wherein, ugDAnd ugQVoltage respectively on the static DQ coordinate system of two-phase, uDhAnd uQhIt is high frequency voltage to be extracted
Signal,WithIt is network voltage positive-sequence component；When initial, high-frequency voltage signal uDh, high-frequency voltage signal uQh, power grid electricity
Positive pressure order componentsWith network voltage positive-sequence componentValue be set as zero.
S62, high-pass filter is utilizedThe error voltage signal u that step S61 is obtainedgDerr1And error voltage signal
ugQerr1It is filtered, obtains error voltage signal ugDerrWith error voltage signal ugQerr:
Wherein, ω0For the synchronization angular frequency of power grid,θ0For the angle of power grid,S is to draw
General Laplacian operater.
S63, the error voltage signal u obtained according to step S62gDerrWith error voltage signal ugQerrCalculate high frequency voltage
Signal uDh, high-frequency voltage signal uQh, network voltage positive-sequence componentNetwork voltage positive-sequence component
Wherein, ωhc,uFor high-frequency voltage signal uDhExtraction unit and high-frequency voltage signal uQhThe cutoff frequency of extraction unit,
ωc,uFor network voltage positive sequence voltageExtraction unit and network voltage positive sequence voltageThe cutoff frequency of extraction unit, ω0For
The synchronization angular frequency of power grid,θ0For the angle of power grid,J represents imaginary number, and s is Laplce's calculation
Son.
S64, the high-frequency voltage signal u for obtaining step S63Dh, high-frequency voltage signal uQh, network voltage positive-sequence component
With network voltage positive-sequence componentIt substitutes into step S61, updates error voltage signal ugDerr1With error voltage signal ugQerr1。
S65, step S61 to step S64 is repeated, out of service when reaching the command signal of setting, output mentions
High-frequency voltage signal u after takingDhWith high-frequency voltage signal uQh。
S7, it is sampled to obtain three-phase current i using electric current of the current sensor to gird-connected inverter grid sidega, three-phase
Electric current igbWith three-phase current igc, and according to formula (13) by three-phase current iga, three-phase current igbWith three-phase current igcIt transforms to
In the static DQ coordinate system of two-phase, obtaining two current components is respectively electric current igDWith electric current igQ:
S8, as shown in Figure 4 and Figure 5, the electric current i that step S7 is obtainedgDWith electric current igQI is substituted into respectivelyDhExtraction module and iQh
Extraction module, by improved complex filter respectively to iDhExtraction module and iQhExtraction module extracts operation, obtains high
Frequency current signal iDhWith high-frequency current signal iQh, the specific steps of which are as follows:
S81, the electric current i obtained using step S7gDWith electric current igQCalculate separately error current signal igDerr1With error electricity
Flow signal igQerr1:
Wherein, igDAnd igQElectric current respectively under the static DQ coordinate system of two-phase, iDhAnd iQhIt is high-frequency current to be extracted
Signal,WithIt is power network current positive-sequence component；When initial, high-frequency current signal iDh, high-frequency current signal iQh, power grid electricity
Flow positive-sequence componentWith power network current positive-sequence componentValue be set as zero.
S82, high-pass filter is utilizedThe error current signal i that step S81 is obtainedgDerr1With error current signal
igQerr1It is filtered, obtains error current signal igDerrWith error current signal igQerr:
S83, the error current signal i obtained according to step S82gDerrWith error current signal igQerrCalculate high-frequency current
Signal iDh, high-frequency current signal iQh, power network current positive-sequence componentPower network current positive-sequence component
Wherein, ωhc,iFor high-frequency current signal iDhExtraction unit and high-frequency current signal iQhThe cutoff frequency of extraction unit,
And ωhc,i=ωhc,u, ωc,iFor power network current positive-sequence componentExtraction unit and power network current positive-sequence componentExtraction unit
Cutoff frequency, ωc,i=ωc,u。
S84, the high-frequency current signal i for obtaining step S83Dh, high-frequency current signal iQh, power network current positive-sequence component
With power network current positive-sequence componentIt substitutes into step S81 and updates error current signal igDerr1With error current signal igQerr1。
S85, step S81 to step S84 is repeated, out of service when reaching the command signal of setting, output mentions
High-frequency current signal i after takingDhWith high-frequency current signal iQh。
S9, the high-frequency voltage signal u obtained according to step S6Dh, high-frequency voltage signal uQhThe high-frequency electrical obtained with step S8
Flow signal iDh, high-frequency current signal iQhCalculate the resistance value of the power grid of gird-connected inverterAnd inductance valueAnd then obtain power grid
Impedance value.Wherein, the resistance value of power gridAnd inductance valueCalculating method method such as formula (17) shown in:
In order to verify effectiveness of the invention, simulating, verifying has been carried out.Emulation uses the DC voltage of gird-connected inverter
udcFor 700V, gird-connected inverter side outputting inductance LiIt is 15.6 μ F, damping resistance R for 5mH, filter capacitor CdFor 2 Ω, power grid angle
Frequencies omega0For 314rad/s, power grid phase voltage amplitude is 311V, the high-frequency signal amplitude U of injectionhHigh frequency for 121V, injection is believed
Number frequency is 3424rad/s, cutoff frequency ωhc,uWith cutoff frequency ωhc,iFor 400rad/s, cutoff frequency ωc,uAnd cutoff frequency
Rate ωc,iFor 221rad/s, setting electric current idrefWith electric current iqrefReference value be respectively 40A and 0A.It is of the invention in order to verify
Validity, with the document [electric network impedance based on multimode complex filter under Yang Ying, Zhang Xing, Li Ming is uneven and harmonic
Detection method [J] power supply journal, 2018,16 (2): 69-75.] suggesting plans has carried out comparative study.When emulation, power grid resistance
RgIt is set as 1 Ω, power grid inductance LgIt is uprushed in 0.4s by 1.2mH as 2.4mH, by 2.4mH anticlimax is 1.2mH in 0.8s.Emulation
When, for the direct current biasing introduced in the sampling channel of analog voltage and the sampling channel of electric current, in the network voltage u of measurementga
On be superimposed voltage be 25V direct current biasing.Fig. 7 and Fig. 8 gives document, and [Yang Ying, Zhang Xing, Li Ming are uneven and harmonic wave is electric
Electric network impedance detection method [J] power supply journal off the net based on multimode complex filter, 2018,16 (2): 69-75.] it is mentioned
The electric network impedance identification and simulation of scheme is as a result, Fig. 9 and Figure 10 give the electric network impedance identification and simulation result of the present invention program.It is right
Than as it can be seen that document [the electric network impedance inspection under Yang Ying, Zhang Xing, Li Ming imbalance and harmonic based on multimode complex filter
Survey method [J] power supply journal, 2018,16 (2): 69-75.] it suggests plans due to not accounting for the direct current biasing in sampling channel
Influence, cause to fluctuate in the electric network impedance of identification containing biggish fundamental frequency, identification precision is poor.And the present invention is due to considering
The influence of direct current biasing in sampling channel, and direct current biasing is inhibited by high-pass filter, to eliminate direct current
The influence recognized to electric network impedance is biased, electric network impedance identification precision is improved.
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all in essence of the invention
Within mind and principle, any modification, equivalent replacement, improvement and so on be should all be included in the protection scope of the present invention.
Claims (9)
1. a kind of gird-connected inverter electric network impedance discrimination method based on high frequency electrocardiography, which is characterized in that its step are as follows:
S1, it is sampled to obtain the line voltage u of gird-connected inverter using power grid of the voltage sensor to gird-connected invertergabAnd line
Voltage ugbc, the phase voltage u of three phase network is calculatedga, phase voltage ugbWith phase voltage ugc, and by phase voltage uga, phase voltage ugb
With phase voltage ugcIt transforms in the static DQ coordinate system of two-phase, obtains voltage ugDWith voltage ugQ, and by voltage ugDWith voltage ugQGeneration
Enter phaselocked loop to obtain the synchronization angular frequency of power grid0And angle, θ0；
S2, sampling acquisition three-phase current i is carried out using bridge arm side electric current of the current sensor to gird-connected invertera, three-phase current ib
With three-phase current ic, and by three-phase current ia, three-phase current ibWith three-phase current icIt transforms in the static DQ coordinate system of two-phase, obtains
It is respectively electric current i to two current componentsDWith electric current iQ, recycle angle, θ0By electric current iDWith electric current iQIt is mapped to synchronous rotary dq
It is respectively electric current i that two current components are obtained on coordinate systemdWith electric current iq；
S3, setting electric current reference value are electric current idrefWith electric current iqref, by electric current idref, electric current iqrefThe electric current obtained with step S2
id, electric current iqThe modulated voltage signal u in synchronous rotary dq coordinate system is obtained by pi controllerdrefAnd modulation voltage
Signal uqref, then by modulated voltage signal udrefWith modulated voltage signal uqrefIt transforms to and is adjusted in the static DQ coordinate system of two-phase
Voltage signal u processedDrefWith modulated voltage signal uQref；
S4, the modulated voltage signal u for obtaining step S3DrefWith modulated voltage signal uQrefTransform to three phase static abc coordinate system
In, obtaining three modulated voltage signals is respectively modulated voltage signal uaref, modulated voltage signal ubrefAnd modulated voltage signal
ucref, then by high-frequency signal uah, high-frequency signal ubhWith high-frequency signal uchIt is injected separately into modulated voltage signal uaref, modulation voltage letter
Number ubrefWith modulated voltage signal ucrefObtaining three-phase modulations voltage signal is respectively modulated voltage signal uahref, modulation voltage letter
Number ubhrefWith modulated voltage signal uchref；
S5, the modulated voltage signal u for obtaining step S4ahref, modulated voltage signal ubhrefWith modulated voltage signal uchrefInput
To PWM modulation unit, 6 road pwm signals are exported, and by the control system in gird-connected inverter are input to pwm signal grid-connected
In inverter, the voltage u in step S1 is updatedgDWith voltage ugQ；
S6, the voltage u for obtaining step S5gDWith voltage ugQU is substituted into respectivelyDhExtraction module and uQhExtraction module, utilization are improved
Complex filter is respectively to uDhExtraction module and uQhExtraction module extracts operation, obtains high-frequency voltage signal uDhAnd high frequency
Voltage signal uQh；
S7, it is sampled to obtain three-phase current i using electric current of the current sensor to gird-connected inverter grid sidega, three-phase current
igbWith three-phase current igc, and by three-phase current iga, three-phase current igbWith three-phase current igcTransform to the static DQ coordinate system of two-phase
In, obtaining two current components is respectively electric current igDWith electric current igQ；
S8, the electric current i for obtaining step S7gDWith electric current igQI is substituted into respectivelyDhExtraction module and iQhExtraction module, by improved
Complex filter is respectively to iDhExtraction module and iQhExtraction module extracts operation, obtains high-frequency current signal iDhAnd high frequency
Current signal iQh；
S9, the high-frequency voltage signal u obtained according to step S6Dh, high-frequency voltage signal uQhThe high-frequency current letter obtained with step S8
Number iDh, high-frequency current signal iQhCalculate the resistance value of the power grid of gird-connected inverterAnd inductance valueAnd then obtain the resistance of power grid
Anti- value.
2. the gird-connected inverter electric network impedance discrimination method according to claim 1 based on high frequency electrocardiography, feature
It is, the voltage u in the step S1gDWith voltage ugQAre as follows:
Wherein,Then utilize voltage ugDWith voltage ugQ
The angle, θ of power grid is calculated0Are as follows:The synchronization angular frequency of power grid0Are as follows:
3. the gird-connected inverter electric network impedance discrimination method according to claim 1 or 2 based on high frequency electrocardiography, special
Sign is, the electric current i in the step S2dWith electric current iqAre as follows:
Wherein,
4. the gird-connected inverter electric network impedance discrimination method according to claim 3 based on high frequency electrocardiography, feature
It is, the modulated voltage signal u in the step S3DrefWith modulated voltage signal uQrefAre as follows:
Wherein,k1For proportional and integral controller
Proportionality coefficient, k2For the integral coefficient of proportional and integral controller, s is Laplace operator.
5. the gird-connected inverter electric network impedance discrimination method according to claim 4 based on high frequency electrocardiography, feature
It is, the modulated voltage signal u in the step S4ahref, modulated voltage signal ubhrefWith modulated voltage signal uchrefRespectively
Are as follows:
Wherein,UhFor
The amplitude of the high-frequency signal injected, t represent the time.
6. the gird-connected inverter electric network impedance discrimination method according to claim 1 based on high frequency electrocardiography, feature
It is, the high-frequency voltage signal u in the step S6DhWith high-frequency voltage signal uQhExtracting method are as follows:
S61, the voltage u obtained using step S5gDWith voltage ugQCalculate separately error voltage signal ugDerr1And error voltage signal
ugQerr1:Wherein, ugDAnd ugQVoltage respectively on the static DQ coordinate system of two-phase, uDhAnd uQh?
For high-frequency voltage signal to be extracted,WithIt is network voltage positive-sequence component；
S62, high-pass filter is utilizedThe error voltage signal u that step S61 is obtainedgDerr1And error voltage signal
ugQerr1It is filtered, obtains error voltage signal ugDerrWith error voltage signal ugQerr:
S63, the error voltage signal u obtained according to step S62gDerrWith error voltage signal ugQerrCalculate high-frequency voltage signal
uDh, high-frequency voltage signal uQh, network voltage positive-sequence componentNetwork voltage positive-sequence component
Wherein, ωhc,uFor high-frequency voltage signal uDhExtraction unit and high-frequency voltage signal uQhThe cutoff frequency of extraction unit, ωc,u
For network voltage positive sequence voltageExtraction unit and network voltage positive sequence voltageThe cutoff frequency of extraction unit, ω0For power grid
Synchronization angular frequency,θ0For the angle of power grid,J represents imaginary number；
S64, the high-frequency voltage signal u for obtaining step S63Dh, high-frequency voltage signal uQh, network voltage positive-sequence componentAnd electricity
Net voltage positive-sequence componentIt substitutes into step S61, updates error voltage signal ugDerr1With error voltage signal ugQerr1；
S65, step S61 to step S64 is repeated, it is out of service when reaching the command signal of setting, after output is extracted
High-frequency voltage signal uDhWith high-frequency voltage signal uQh。
7. the gird-connected inverter electric network impedance discrimination method according to claim 1 based on high frequency electrocardiography, feature
It is, the electric current i in the step S7gDWith electric current igQAre as follows:
8. the gird-connected inverter electric network impedance discrimination method according to claim 1 or 6 based on high frequency electrocardiography, special
Sign is, the high-frequency current signal i in the step S8DhWith high-frequency current signal iQhExtracting method are as follows:
S81, the electric current i obtained using step S7gDWith electric current igQCalculate separately error current signal igDerr1With error current signal
igQerr1:Wherein, igDAnd igQElectric current respectively under the static DQ coordinate system of two-phase, iDhAnd iQhIt is
High-frequency current signal to be extracted,WithIt is power network current positive-sequence component；
S82, the error current signal i that step S81 is obtained using high-pass filtergDerr1With error current signal igQerr1It carries out
Filtering processing, obtains error current signal igDerrWith error current signal igQerr:
S83, the error current signal i obtained according to step S82gDerrWith error current signal igQerrCalculate high-frequency current signal
iDh, high-frequency current signal iQh, power network current positive-sequence componentPower network current positive-sequence component
Wherein, ωhc,iFor high-frequency current signal iDhWith high-frequency current signal iQhThe cutoff frequency of extraction unit, and ωhc,i=
ωhc,u, ωc,iFor power network current positive-sequence componentWith power network current positive-sequence componentThe cutoff frequency of extraction unit, ωc,i=
ωc,u；
S84, the high-frequency current signal i for obtaining step S83Dh, high-frequency current signal iQh, power network current positive-sequence componentAnd power grid
Electric current positive-sequence componentIt substitutes into step S81 and updates error current signal igDerr1With error current signal igQerr1；
S85, step S81 to step S84 is repeated, it is out of service when reaching the command signal of setting, after output is extracted
High-frequency current signal iDhWith high-frequency current signal iQh。
9. the gird-connected inverter electric network impedance discrimination method according to claim 8 based on high frequency electrocardiography, feature
It is, the resistance value of the power gridAnd inductance valueAre as follows:
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